The present invention relates to a vehicle wheel, comprising a wheel disk fabricated as a casting, preferably casted from lightweight metal, with a disk edge running concentrically around a wheel axis and a rim ring, preferably fabricated from steel, rotationally locked to the wheel disk and having at least one rim flange, at least one bead seat, one drop center rim well base and at least a well base edge, for seating a tire on the outside of the rim ring. The invention also relates to a method for manufacturing such a hybrid vehicle wheel from a wheel disk fabricated as a casting, preferably from lightweight metal, and a rim ring, preferably of steel, in operations entailing the provision of a rim ring preform having at least one rim flange, a bead seat, a rim well base and a well base edge, and the provision of a wheel disk, which has a disk edge running concentrically around the wheel axis. The invention is intended, in particular, for vehicle wheels for motor vehicles, especially passenger automobiles.
In the state of the art the trend with vehicle wheels has firstly been towards the conventional steel vehicle wheels comprising a steel rim ring, largely manufactured by metal forming processes on a production line, and a steel wheel disk manufactured on a separate production line, which at the end of the production lines are welded together to form the vehicle wheel. The rim ring and the wheel disk here each take on their final form on the production line before being welded together.
In addition, in the state of the art there has been a trend towards lightweight metal wheels, especially of aluminum, which are manufactured as integrally cast constructions or as wheel forgings. In the case of multipart lightweight metal wheels a cast or forged wheel disk is joined to a rim of aluminum strip manufactured by profile rolling or roll forming. They can either be joined by detachable bolted connections or welded.
DE 100 58 807 A1 discloses a hybrid vehicle wheel in which the wheel disk and the rim ring are produced from different materials and the wheel disk and the rim ring are joined together by friction welding. DE 198 04 739 A1, for example, discloses the provision, in a wheel disk fabricated from lightweight metal, of an outer rim flange integrally formed on the disk, and the formation of a welded-on extension to the wheel disk in the area of the outer bead seat, a rim ring, correspondingly formed without the outer rim flange, then being attached thereto by friction welding.
A vehicle wheel of generic type is disclosed by DE 82 16 339 U1. In the case of this vehicle wheel a wheel disk is manufactured as a casting, onto which a rim ring comprising all the elements of a wheel rim is then fitted by shrinking on. The shrinking-on is intended to achieve a press fit between the rim ring and the wheel disk, bearing with its circumferential edge against the inside of the rim ring of the bead seat, which rotationally locks the wheel disk and the rim ring together. In order to increase the friction in the press fit between the ring rim and the wheel disk, granular material, projections or a heat-resistant adhesive lacquer can be introduced into the opposing faces. In the area of the bead seat, which on the outside of the ring has an inclination of approximately 5° in the case of vehicle wheels and an inclination of approximately 15° in the case of commercial vehicle wheels (tapered seat wheels), the rim ring must be provided with an additional material thickening, in order that the rim ring can taper conically in diameter on the inside of the ring from the well base edge to the outside of the wheel. In order to be able to shrink the rim ring onto the wheel disk, the rim ring must be heated to temperatures in excess of 300°, which is extremely costly in terms of energy and results in high production costs. Other disadvantages beside the high production costs are that the high temperatures which have to be applied can cause material changes in the preferably formed rim ring, and in addition an anticorrosion protection, which before joining together has been applied at joining sites that are subsequently no longer accessible, is destroyed by the high temperatures, so that the vehicle wheel fabricated by shrinking on is highly susceptible to corrosion, especially at the joining sites.